Adam Gopnik deconstructs the submerged iceberg and unique snowflake metaphors. From Winter: Five Windows on the Season, the 2011 Massey Lectures, published by Anansi in Fall 2011.

Oh yes, what about those two metaphors? Have they survived their century? The submerged nine-tenths of the iceberg and those singular snowflakes? Well, we know now that those final discoveries of the Romantic imagination of winter are both touched with more than a little myth. The mysterious, sinister, stiletto-bearing iceberg that can stab ships in the back turns out, in fact, to be largely imaginary. The nine-tenths of the iceberg sunk beneath the water simply follows a natural rule of physics and is not a peculiarity of glaciology. And far from having stuck a stiletto into the side of the Titanic, we now know that the iceberg in question merely crushed it, like an awkward adolescent boy at a dance, popping the rivets and stays of the great ship. The iceberg is neither the radio beacon of earth consciousness nor the white shark of the seas, but just a great big, overgrown ice cube, as innocent (and dumb) as ice cubes are. And, in parallel, we might say that though “iceberg psychology” and its notion of uncon­scious motives still haunt us, the coming of cognitive psychology has also taught us that the overt and explicit part of thought mat­ters most. It’s the part of the iceberg you do see that sinks your psychic ship.

And snowflakes? Are they all unlike? And does that difference give us some natural evidence for individuality? It turns out that, as recently as 1988, a cloud scientist named Nancy Knight took a plane up into the clouds above Madison, Wisconsin, and there found two simple but identical snow crystals—hexagonal prisms, each as like the other as one Olsen twin is like the other. Snowflakes, it seems, are not only alike, they usually start out more or less the same. But if this notion threatens to be depress­ing—it was only the happy eye of nineteenth-century optimism that saw radical individuality there—one can in the end put a brighter spin on things. It turns out that, while it’s true that snowflakes often start out alike, it is their descent from the clouds into the world that makes them alter. (“As a snowflake falls, it tumbles through many different environments. So the snowflake that you see on the ground is deeply affected by the different tem­peratures, humidities, velocities, turbulences, etc., that it has experienced on the way,” Australian science writer Karl Kruszelnicki writes.) Their different shapes are all owed to their different paths downwards. So snowflakes actually start off all alike; it is experience that makes each one just different enough to be noticed.

In a way, the passage from “Snowflake” Bentley [Wilson Bentley, a nineteenth-century Vermont man with an obsessive devotion to snow and snowflakes] to the new snowflake stories is typical of the way our vision of nature has changed over the past century: Bentley . . . believed in the one fixed and telling image; we believe in truths revealed over time—not what animals or snowflakes or icebergs really are, mystically fixed, but how they have altered to become what they are. Those ice flowers formed on that long-ago German window really are like life, in the end, if only because they are lucky to be here, and at the mercy of the elements, as we all are. The sign at Starbucks should read “Friends Are Like Snowflakes: More Different and Beautiful Each Time You Cross Their Path in Our Common Descent.” For the final truth about snowflakes is that they become more individual as they fall; that, buffeted by wind and time, they are translated, as if by magic, into ever stranger and more complex patterns, until at last they touch earth. Then, like us, they melt.